Device for cooling a supporting structure of a heat shield, and heat shield

Abstract

A device (20, 29, 48, 64) for cooling a supporting structure of a heat shield (33, 60) to avoid scaling of the supporting structure due to the intake of hot gas. The device has a longitudinal axis (21) and a cooling air duct (22). The device is on the supporting structure with the longitudinal axis (21) intersecting the surface (51) of the supporting structure (34). In this position, the cooling air duct (22) extends from a device end (23) pointing towards the supporting structure. The device has at least one outlet duct downstream in the cooling air duct. The duct emerges out of the device (20, 29, 48, 64) laterally with respect to the longitudinal axis (21). The cooling air duct (22) corresponds to at least one cooling air passage (50) in the supporting structure (34).

Claims

1. A heat shield cooling device for a combustion chamber of a gas turbine, the cooling device comprising: a supporting structure, a plurality of heat shield tiles, tile holders releasably attaching the plurality of heat shield tiles to the supporting structure; each heat shield tile of the plurality of heat shield tiles has a cold side oriented towards the supporting structure and an opposite hot side which is exposed to a hot medium; each tile holder has a holding section for attaching to a heat shield tile of the plurality of heat shield tiles and an attachment section attached to the supporting structure for protecting the supporting structure from effects of hot gases; at least one cooling air passage arranged in the supporting structure; a post with a longitudinal axis and a cooling air duct extending through the post, the post is arranged on at least one of the at least one cooling air passage and the at least one of the at least one cooling air passage communicates cooling air into the cooling air duct for cooling the supporting structure; the post is on the supporting structure and is above a surface of the supporting structure, the cooling air duct extends through the post from the at least one of the at least one cooling air passage, downstream to at least one outlet duct that exits the post laterally with respect to the longitudinal axis; and the post on the supporting structure is located beneath a heat shield tile of the plurality of heat shield tiles, such that the at least one outlet duct of the post opens into an interspace between the cold side of the heat shield tile of the plurality of heat shield tiles and the supporting structure wherein the attachment section extends from the surface of the supporting structure at the post along a direction within the interspace, and the direction comprises a direction component parallel to the surface of the supporting structure.

2. The heat shield cooling device as claimed in claim 1, wherein the at least one outlet duct runs radially with respect to the longitudinal axis.

3. The heat shield cooling device as claimed in claim 1, further comprising at least two oppositely directed ones of the at least one outlet ducts.

4. The heat shield cooling device as claimed in claim 2, wherein the post has four of the at least one outlet ducts.

5. The heat shield cooling device as claimed in claim 1, further comprising: attachment slots running in the supporting structure, the attachment sections of the tile holders are releasably attached in the attachment slots; and the at least one cooling air passage opens into a bottom of the attachment slot, and the post is arranged in the bottom of the attachment slot at the at least one cooling air passage.

6. The heat shield cooling device as claimed in claim 5, further comprising the post is between two of the attachment sections of the tile holders.

7. The heat shield as claimed in claim 5, further comprising a cooling air slot in the bottom of the attachment slot, the post is sunk into the at least one of the at least one cooling air passage at least at the level of the bottom of the attachment slot, and the at least one outlet ducts of the post open into the cooling air slot.

8. The heat shield cooling device as claimed in claim 7, further comprising the cooling air slot comprises a runout at each ends of the cooling air slot.

9. The heat shield cooling device as claimed in claim 1, further comprising the supporting structure and the post are aligned such that the post is sunk into the supporting structure for enabling installing and removing of the plurality of heat shield tiles without interference from the post.

10. A combustion chamber which is clad with a heat shield, wherein the heat shield cooling device is as claimed in claim 1.

11. A gas turbine with at least one combustion chamber, wherein the at least one combustion chamber is as claimed in claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the figures:

(2) FIG. 1 is a schematic representation of a gas turbine according to the prior art,

(3) FIG. 2 is a schematic sectional view of a device according to the invention for cooling a supporting structure of a heat shield, according to a first exemplary embodiment,

(4) FIG. 3 is a schematic sectional view through a device according to the invention for cooling the supporting structure, according to a second exemplary embodiment,

(5) FIG. 4 is a schematic sectional view of a device according to the invention, according to a third exemplary embodiment,

(6) FIG. 5 is a schematic sectional view of a detail of a heat shield according to the invention arranged on the supporting structure with a device for cooling the supporting structure, according to a fourth exemplary embodiment,

(7) FIG. 6 is a schematic sectional view of the heat shield represented in FIG. 5 along a plane denoted by the arrows VI-VI in FIG. 5,

(8) FIG. 7 is a schematic sectional view of a detail of a heat shield according to a fifth exemplary embodiment in a section view, and

(9) FIG. 8 is a schematic sectional view of the heat shield represented in FIG. 7 along a plane denoted by the arrows VIII-VIII in FIG. 7.

DESCRIPTION OF EMBODIMENTS

(10) FIG. 1 is a schematic sectional view of a gas turbine 1 according to the prior art. The gas turbine 1 has, internally, a rotor 3 which is mounted to rotate about an axis of rotation 2 and which also has a shaft 4 which is also termed the turbine rotor. Along the rotor 3 there are, in sequence, an intake casing 6, a compressor 8, a combustion system 9 with a number of combustion chambers 10 which each comprise a burner arrangement 11 and a casing 12, a turbine 14 and an exhaust casing 15. For protection from hot gases, the casing 12 is clad with a heat shield (not shown).

(11) The combustion system 9 communicates with for example an annular hot gas duct. There, multiple series-connected turbine stages form the turbine 14. Each turbine stage is formed from blade rings. As seen in the flow direction of a working medium, in the hot duct a row formed of stator vanes 17 alternates with a row formed of rotor blades 18. The stator vanes 17 are attached to an internal casing of a stator 19, whereas the rotor blades 18 of a row are attached to the rotor 3 by means of a turbine disk for example. Coupled to the rotor 3 is for example a generator (not shown).

(12) When the gas turbine is in operation, air is drawn in by the compressor 8 through the intake casing 6 and compressed. The compressed air which is made available at the turbine-side end of the compressor 8 is directed to the combustion system 9 and there it is mixed with fuel in the region of the combustion arrangement 11. The mixture is then combusted in the combustion system 9, with the aid of the combustion arrangement 11, forming a working gas flow. Thence, the working gas flow flows along the hot gas duct past the stator vanes 17 and the rotor blades 18. On the rotor blades 18, the working gas flow expands, transmitting an impulse so that the rotor blades 18 drive the rotor 3 and this drives the generator (not shown) which is coupled to the latter.

(13) FIG. 2 shows, schematically, in a section view a device 20 according to the invention for cooling a supporting structure of a heat shield, according to a first exemplary embodiment. The device 20 has a longitudinal axis 21 and comprises a cooling air duct 22. The cooling air duct 22 extends from one end 23 of the device and comprises, downstream, two outlet ducts 25a and 25b which exit the device laterally with respect to the longitudinal axis 21 and which are arranged opposite one another. According to the represented exemplary embodiment, the device may be a post, and more particularly the post may be set screw with a cooling air duct 22 running inside the set screw. The represented device 20 can also be termed a cooling grub. The set screw has, on its lateral surface 26, a thread (not shown). The thread can for example extend in the region of the end 23 over the lateral surface 26 or extend to the opposite end 27. The device 20 can be arranged with its end 23 on a supporting structure of a heat shield. For example, the post, set screw or cooling grub is screwed into a cooling air bore, provided with an internal thread, in the supporting structure. In this position, cooling air issuing from the cooling air bore can be guided into the cooling air duct 22, such that the cooling air flows downstream through the outlet ducts 25a, 25b, and leaves the cooling grub in the directions labeled 24a and 24b.

(14) FIG. 3 shows a cross section of a device 29 according to the invention for cooling a supporting structure, according to a second exemplary embodiment of the invention. The cross section runs perpendicular to the longitudinal axis 21 at the level of the outlet ducts 30a and 30b. The represented device 29 differs from the post, set screw or cooling grub represented in FIG. 2 only in the angle with respect to the longitudinal axis 21 at which the outlet ducts 30a and 30b leave the device laterally. In the represented exemplary embodiment, the outlet ducts run radially with respect to the longitudinal axis 21 and are arranged opposite one another. Cooling air flowing through the cooling air duct 22 is divided downstream into the outlet ducts 30a and 30b, and exits the cooling grub in the represented outflow directions 31a and 31b.

(15) FIG. 4 shows a cross section of a device 64 according to the invention for cooling a supporting structure, according to a third exemplary embodiment of the invention. The cross section runs perpendicular to the longitudinal axis 21 at the level of the outlet ducts 66a, 66b, 66c and 66d. The represented device 64 differs from the post, set screw or cooling grub represented in FIG. 3 only in the number of outlet ducts. The represented exemplary embodiment comprises four outlet ducts which run radially with respect to the longitudinal axis 21 and are arranged in pairs opposite one another. Cooling air flowing through the cooling air duct 22 is divided downstream into the outlet ducts 66a, 66b, 66c and 66d, and exits the cooling grub 64 in the represented directions 67a, 67b, 67c and 67d.

(16) FIG. 5 shows a detail of a heat shield 33 according to the invention with a supporting structure 34 and a number of heat shield tiles, of which a heat shield tile 35 is represented by way of example in the figure. The heat shield tile 35 has a cold side 36 oriented towards the supporting structure 34 and a hot side 37 which is opposite the cold side 36 and which can be exposed to a hot medium. The heat shield tile 35 is attached to the supporting structure 34 by means of tile holders 38 and 39. To that end, the tile holders 38, 39 on one hand are attached to the supporting structure 34 with their attachment sections 40, 41 and on the other hand grip with their holding sections 42, 43 in holding slots 44, 47 on opposing sidewalls of the heat shield tile 35. With the heat shield tile 35 resiliently held on the supporting structure 34 in this manner, when the hot side 37 is exposed to hot gases, it is possible for the hot gases to enter the expansion gaps between adjacent heat shield tiles. The gases penetrating in the direction 45 then propagate beneath the heat shield tile 35 in the interspace 46 which extends from the cold side 36 of the heat shield tile 35 to a surface region of the supporting structure 34 facing the heat shield tile 35. This can result in scaling of the supporting structure 34 beneath the heat shield tile 35.

(17) To provide protection from hot gases, a device 48 according to the invention for cooling the supporting structure 34 is arranged on the supporting structure 34 beneath the heat shield tile. According to the represented exemplary embodiment, the device 48 according to the invention is a post, set screw or cooling grub with a longitudinal axis 21 and a cooling air duct 22. The device 48 can thus also be termed a cooling grub 48. The post, set screw or cooling grub 48 is arranged on the supporting structure with its longitudinal axis 21 perpendicular to the surface 51 of the supporting structure, wherein the post cooling grub 48 is screwed into a cooling air passage 50 of the supporting structure with an end 23 oriented towards the supporting structure. The cooling air passage 50 is embodied as a cooling air bore. The cooling air duct 22 extends from the screwed-in end 23 and comprises, downstream, two outlet ducts 52a, 52b which exit the cooling grub 48 laterally with respect to the longitudinal axis 21. The cooling air bore 50 and the cooling air duct 22 line up with each other so that cooling air flowing out of the cooling air bore enters the cooling air duct 22 and, by means of the cooling grub 48, flows in the directions 53a, 53b into the interspace 46. The cooling air is thus introduced beneath the heat shield tile 35 far from the expansion gaps. This permits particularly effective cooling of the supporting structure. In addition, according to the invention, impingement cooling of the heat shield tile 35 is avoided. Since the post, set screw or cooling grub 48 in the represented exemplary embodiment is arranged between two attachment sections 40, 41 of the tile holders 38, 39, centrally beneath the heat shield tile 35, in particular those regions of the supporting structure to which the tile holders are attached are cooled. It is also possible for the length of the cooling air bore 50 to be chosen such that the cooling grub 48 can be entirely sunk into the former during installation and removal of the heat shield tiles.

(18) FIG. 6 shows the heat shield 33 represented in FIG. 5, in a further section view along the plane denoted by the arrows VI-VI. This view shows that the tile holders are held on the supporting structure 34 with their attachment sections in an attachment slot 55. The post, set screw or cooling air bore 50 opens into the bottom 56 of this attachment slot 55. The cooling grub 48 is arranged in the bottom 56 of the slot at the cooling air bore 50 with the longitudinal axis 21 perpendicular to the surface 51 of the supporting structure 34, and projects by a portion 58 out of the bottom 56 of the slot. The portion 58 is in this case chosen such that the post, set screw or cooling grub 48 does not touch the cold side 36 of the heat shield tile 35 and such that the cooling air flows out of the outlet ducts 52a, 52b into the attachment slot 55 and, on account of the position of the cooling grub 48 arranged between the tile holders, enters the interspace 46.

(19) FIG. 7 shows a detail of a heat shield 60 according to the invention, according to a fifth exemplary embodiment. This differs from that represented in FIG. 5 in that, in addition, a cooling air slot 62 runs in the bottom of the attachment slot. The post, set screw or cooling grub 48 is sunk into the cooling air bore 50 to the level of the bottom of the attachment slot, wherein the outlet ducts 52a, 52b of the post, set screw or cooling grub 48 open into the cooling air slot 62 in the longitudinal direction. This has the advantage that the tile holders can be moved away through the attachment slot, over the post, set screw or cooling grub 48 for installing and removing the heat shield tiles 35. The function of the cooling grub 48 is thus maintained. The cooling air which flows out of the cooling grub 48 and whose flow directions are represented for the sake of example with arrows, is injected into the cooling air slot 62 and flows at the ends thereof by means of a runout 63 into the interspace 46 between the cold side of the heat shield tile 35 and the supporting structure 34 and cools the supporting structure 34 beneath the heat shield tile 35 while avoiding impingement cooling of the latter.

(20) FIG. 8 shows the heat shield 60 represented in FIG. 7 in a section view along the plane denoted by the arrows VIII-VIII. The tile holders (not shown in this view) which attach the heat shield tiles 35 to the supporting structure 34 are held on the supporting structure 34 with their attachment sections in the attachment slot 55. The cooling air bore 50 opens into the bottom 56 of this attachment slot 55. The post, set screw or cooling grub 48 is arranged in the bottom 56 of the slot at the cooling air bore 50 with the longitudinal axis 21 perpendicular to the surface 51 of the supporting structure 34, and is sunk into the cooling air bore 50 to the level of the bottom 56 of the slot. It is thus possible for the tile holders to be displaced freely in the attachment slot 55 for installing and removing the heat shield tiles 35. The cooling air issuing from the outlet ducts 52a, 52b of the post, set screw or cooling grub 48 flows first into the cooling air slot 62 and thence into the interspace 46. There, the cooling air can spread and effectively cool the supporting structure beneath the heat shield tile 35.